Upgrading to Kerberos V5 from Kerberos V4

Release: 1.2

Document Edition: 1.0

Last updated: October 8, 1996

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@hrule

The following copyright and permission notice applies to the OpenVision
Kerberos Administration system located in kadmin/create, kadmin/dbutil,
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@hrule

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@hrule

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@pagealignmacro

As with most software upgrades, Kerberos V5 is generally backward
compatible but not necessarily forward compatible. The Kerberos V5
daemons can interoperate with Kerberos V4 clients, but most of the
Kerberos V4 daemons can not interoperate with Kerberos V5 clients. This
suggests the following strategy for performing the upgrade:

Upgrade your KDCs. This is must be done first, so that
interactions with the Kerberos database, whether by Kerberos V5 clients
or by Kerberos V4 clients, will succeed.

Upgrade your servers. This must be done before upgrading
client machines, so that the servers are able to respond to both
Kerberos V5 and Kerberos V4 queries.

Upgrade your client machines. Do this only after your KDCs and
application servers are upgraded, so that all of your Kerberos V5
clients will be talking to Kerberos V5 daemons.

If you used the defaults, both when you installed Kerberos V4 and when
you installed Kerberos V5, you should not need to include any of
these tags. However, some or all of them may be necessary for
nonstandard installations.

Identifies the default domain for hosts in this realm. This is needed
for translating V4 principal names (which do not contain a domain name)
to V5 principal names. The default is your Kerberos realm name,
converted to lower case.

v4_instance_convert

This subsection allows the administrator to configure exceptions to the
default_domain mapping rule. It contains V4 instances (tag name) which
should be translated to some specific hostname (tag value) as the second
component in a Kerberos V5 principal name.

v4_realm

This relation allows the administrator to configure a different
realm name to be used when converting V5 principals to V4
ones. This should only be used when running separate V4 and V5
realms, with some external means of password sychronization
between the realms.

To convert your KDCs from Kerberos V4 to Kerberos V5, do the
following:

Install Kerberos V5 on each KDC, according to the instructions in
the Kerberos V5 Installation Guide, up to the point where it tells
you to create the database.

Find the kadmind (V4) daemon process on the master KDC and kill
it. This will prevent changes to the Kerberos database while you
convert the database to the new Kerberos V5 format.

Create a dump of the V4 database in the directory where your V5 database
will reside by issuing the command:

% kdb_util dump /usr/local/var/krb5kdc/v4-dump

Load the V4 dump into a Kerberos V5 database, by issuing the command:

% kdb5_util load_v4 v4-dump

Create a Kerberos V5 stash file, if desired, by issuing the command:

% kdb5_util stash

Proceed with the rest of the Kerberos V5 installation as described
in the Kerberos V5 Installation Guide. When you get to the section
that tells you to start the krb5kdc and kadmind daemons,
first find and kill the Kerberos V4 kerberos daemon on each of
the KDCs. Then start the krb5kdc and kadmind daemons as
directed. Finally, start the Kerberos V5 to V4 ticket translator
daemon, krb524d, by issuing the command:

% /usr/local/sbin/krb524d -m > /dev/null &

If you have a stash file and you start the krb5kdc and
kadmind daemons at boot time, you should add the above line to
your /etc/rc (or /etc/rc.local) file on each KDC.

In the file /etc/inetd.conf, for a secure server, instead
of making the changes described in the Kerberos V5 Installation
Guide, do the following:
Find and comment out any lines for the services ftp,
telnet, shell, login, and exec.
Add the following lines. (Note: each line beginning with => is
a continuation of the previous line.)

N.B.: As noted in the Kerberos V5 Installation Guide, if
you have some clients running older versions of Kerberos V5 (beta 6 or
earlier), checksums were done differently in those versions, which will
cause authentication to fail. To get around this problem, have the
klogind and kshd daemons ignore checksums, by replacing
each -c flag above with -i.
For an insecure server, make the changes described in the
Kerberos V5 Installation Guide.
When you make changes to inetd.conf, remember to kill -HUP
the inetd process to cause the changes to take effect.

Install Kerberos V5 on each client machine, according to the
instructions in the Kerberos V5 Installation Guide.

Tell your users to add the appropriate directory to their paths. On
UNIX machines, this will probably be /usr/local/bin.

Note that if you upgrade your client machines before all of your
application servers are upgraded, your users will need to use the
Kerberos V4 programs to connect to application servers that are still
running Kerberos V4. (The one exception is the UNIX version of
Kerberos V5 telnet, which can connect to a Kerberos V4 and Kerberos
V5 application servers.) Users can use either the Kerberos V4 or
Kerberos V5 programs to connect to Kerberos V5 servers.

Kerberos V5 uses port 88, which is the port assigned by the IETF,
for KDC requests. Kerberos V4 used port 750. If your users will need
to get to any KDCs outside your firewall, you will need to allow TCP and
UDP requests on port 88 for your users to get to off-site Kerberos V5
KDCs, and on port 750 for your users to get to off-site Kerberos V4
KDCs.

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